PARIS, Texas — Gun-rights activists, some of them wearing camouflage and military-style gear and openly toting rifles and handguns, marched alongside the hundreds of people who flocked to downtown Dallas last week to protest police shootings of blacks.

Their presence was part of the new legal landscape in Texas, which earlier this year allowed people to openly carry firearms in public.

Moments later, when a sniper gunned down officers patrolling the peaceful march, killing five, the attack ignited panic and confusion. Who was shooting? Were the people with weapons friend or foe?

It was the same nightmare scenario that some law enforcement officials predicted when Texas approved the open-carry proposal.

Dallas Police Chief David Brown estimated that 20 to 30 open-carry activists attended the rally. He said some wore gas masks, bulletproof vests and fatigues. They ran when the shots rang out, but the presence of so many armed individuals at the scene of a sniper attack caused instant confusion.

“Doesn’t make sense to us, but that’s their right in Texas,” Brown told CNN, adding: “For our officers, they were suspects. And I support that belief. Someone is shooting at you from a perched position, and people are running with AR-15s and camo gear and gas masks and bulletproof vests. They are suspects until we eliminate that.”

One man in the crowd, Mark Hughes, was carrying an AR-style firearm and wearing a camouflage T-shirt. In the early moments after the attack, police released a photo of Hughes describing him as a suspect. He was questioned and released, and authorities soon announced that the attack had been the work of a single gunman named Micah Johnson.

In the aftermath, President Barack Obama criticized the open-carry law.

Forty-five states have laws that allow citizens to openly carry a firearm in public places. During debate over the open-carry issue, some people in Texas law enforcement expressed concerns, fearing that it would lead to panic, especially in active shooter situations. The state, which legalized concealed-carry firearms in the 1990s, now has more than 850,000 residents with licenses to carry.

C.J. Grisham, the president and founder of Open Carry Texas, stood Saturday outside the Lamar County Sheriff’s Department in Paris with a small group of people, most of them with a handgun and spare magazines visible and strapped to a belt. They were there in part to protest the agency’s refusal to allow people to openly carry a firearm into the building, which is connected to a jail, and to talk about what issues are next in gun rights.

Grisham, who served in the military in Iraq and Afghanistan, travels around the state with a trailer in tow. Inside, he’s got T-shirts, stickers and pamphlets that trumpet the group’s key messages.

“We’re not the threat,” Grisham said.

As he spoke, members of the group nodded their heads. They expressed concern that requiring people to carry concealed weapons is sometimes impractical. Texas weather can make it difficult to conceal a gun without wilting in the summer heat or to shed a coat in the winter. That puts them at risk of breaking the law by revealing they are carrying a weapon.

“That’s what this is really about: being able to get comfortable and not become a criminal,” Grisham said. “If you boil it down, the only difference between open carry and concealed carry is a thin piece of fabric.”